Various electromagnetic techniques exist to perform surveys of a subterranean structure for identifying elements of interest. Examples of elements of interest in the subterranean structure include hydrocarbon-bearing reservoirs, gas injection zones, thin carbonate or salt layers, and fresh-water aquifers. One survey technique is the magnetotelluric (MT) survey technique that employs time measurements of electric and magnetic fields (which are responsive to naturally occurring electromagnetic fields) for determining the electrical conductivity distribution beneath the surface. Another survey technique is the controlled source electromagnetic (CSEM) survey technique, in which an electromagnetic transmitter, called a “source,” is used to generate electromagnetic signals. With either survey technique, surveying units, called “receivers,” are deployed on a surface (such as at the sea floor or on land) within an area of interest to make measurements from which information about the subterranean structures can be derived. The receivers may include a number of sensing elements for detecting any combination of electric fields, electric currents, and magnetic fields.
Although EM measurements have enabled operators to identify elements of interest within a subterranean structure, EM surveying can be subject to inaccuracies under certain conditions. For example, equipment failure, mis-positioning of EM receivers or EM sources, or mis-interpretation of EM data may lead to erroneous results.